Cryptocurrency is a type of digital currency that uses cryptography for security and anti-counterfeiting measures. Public and private keys are often used to transfer cryptocurrency between individuals. As a counter-culture movement that is often connected to cypherpunks, cryptocurrency is essentially a fiat currency. This means users must reach a consensus about cryptocurrency's value and use it as an exchange medium. However, because it is not tied to a particular country, its value is not controlled by a central bank. With bitcoin, the leading functioning example of cryptocurrency, value is determined by market supply and demand, meaning that it behaves much like precious metals, like silver and gold. Gavin Andresen, bitcoin's technical lead, told Forbes.com that cryptocurrency is designed to bring back a "decentralized currency of the people," taking centralized banks out of the equation. Because bitcoins must be cryptographically signed each time they are transferred, each bitcoin user has both public and individual private keys. Cryptocurrency transactions are anonymous, untraceable and have created a niche for illegal transactions, like drug trafficking. Because the currency has no central repository, law enforcement and payment processors have no jurisdiction over bitcoin accounts. For cryptocurrency supporters, this anonymity is a primary strength of this technology, despite the potential for illegal abuse, as it enables a shift in power from institutions to individuals.